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Thermal Conductivity vs. Thermal Diffusivity: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on December 25, 2023
Thermal conductivity measures a material's ability to conduct heat, while thermal diffusivity indicates how quickly a material reaches thermal equilibrium.

Key Differences

Thermal conductivity is a property that quantifies how well a material can conduct heat. In contrast, thermal diffusivity measures how quickly a material can spread heat relative to its storage of heat.
A high thermal conductivity implies that a material can transfer heat efficiently, commonly found in metals. Conversely, thermal diffusivity is a measure of how rapidly a temperature change spreads through a material.
Thermal conductivity is typically expressed in watts per meter-kelvin (W/m·K). It's crucial in applications requiring efficient heat transfer. Thermal diffusivity, however, combines thermal conductivity, density, and specific heat capacity, reflecting both conductive and storage properties of materials.
Materials with high thermal conductivity are preferred for heat exchangers and cooling systems. On the other hand, thermal diffusivity is key in determining how quickly a material responds to changes in temperature, important in thermal management.
Thermal conductivity focuses on the rate of heat transfer through a material, thermal diffusivity gives a broader picture, considering how the material absorbs and releases heat.

Comparison Chart


Ability to conduct heat
Speed of reaching thermal equilibrium


Watts per meter-kelvin (W/m·K)
Square meters per second (m²/s)


Dependent on material's nature
Dependent on conductivity, density, and specific heat


Used in designing heat exchangers, insulation
Important in transient heat transfer analysis


Crucial in steady-state heat transfer
Vital in understanding material's thermal response

Thermal Conductivity and Thermal Diffusivity Definitions

Thermal Conductivity

It quantifies the rate of heat flow through a material.
The thermal conductivity of insulation is low, reducing heat loss in homes.

Thermal Diffusivity

Thermal diffusivity combines conductivity, density, and specific heat capacity.
Thermal diffusivity is crucial in materials used for thermal buffering.

Thermal Conductivity

It represents the amount of heat transferred per unit time through a material.
A material's thermal conductivity affects its suitability for thermal insulation.

Thermal Diffusivity

Thermal diffusivity indicates the speed of temperature propagation in a material.
In fire safety, materials with low thermal diffusivity are preferred for their slow heat spread.

Thermal Conductivity

Thermal conductivity is the degree to which a material conducts heat.
The thermal conductivity of a material is a key factor in designing cooling systems.

Thermal Diffusivity

It reflects a material's ability to conduct heat relative to its heat storage capacity.
A high thermal diffusivity means rapid temperature equalization in a substance.

Thermal Conductivity

Thermal conductivity is a material property indicating how easily heat passes through it.
Metals generally have a higher thermal conductivity than plastics.

Thermal Diffusivity

It measures how quickly a material achieves thermal equilibrium.
Materials with low thermal diffusivity are slow to adjust to temperature changes.

Thermal Conductivity

Thermal conductivity measures a material's capacity to conduct heat.
Copper has a high thermal conductivity, making it ideal for heat exchangers.

Thermal Diffusivity

Thermal diffusivity is the rate at which heat spreads through a material.
High thermal diffusivity in a cooking pan ensures quick and even heating.


Why is thermal conductivity important?

It's crucial in applications involving heat transfer.

Are metals generally high or low in thermal conductivity?

Metals usually have high thermal conductivity.

Does thermal diffusivity impact material's response to temperature change?

Yes, it affects how quickly a material responds to temperature changes.

What is thermal conductivity?

It's a measure of a material's ability to conduct heat.

How is thermal conductivity measured?

In watts per meter-kelvin (W/m·K).

How is thermal diffusivity related to heat capacity?

It combines thermal conductivity with material's heat capacity and density.

Can thermal conductivity change with temperature?

Yes, it can vary with temperature.

What units are used for thermal diffusivity?

Square meters per second (m²/s).

Can a material have high conductivity but low diffusivity?

Yes, if it has a high heat capacity or density.

What does thermal diffusivity indicate?

The rate at which heat spreads through a material.

Does thermal conductivity affect a material's suitability for cooking utensils?

Yes, high conductivity is preferred for even heat distribution.

What role does thermal conductivity play in electronics?

It's important for heat dissipation in electronic components.

How does thermal diffusivity relate to fire safety?

Low diffusivity materials are slower to spread heat, beneficial in fire safety.

Do fluids have thermal conductivity and diffusivity?

Yes, these properties are relevant in fluids as well.

Can thermal diffusivity be altered in a material?

Yes, by changing its composition or structure.

Are thermal conductivity and diffusivity considered in environmental studies?

Yes, particularly in studying heat transfer in the earth and atmosphere.

What is a common application of thermal diffusivity?

In analyzing transient heat transfer in materials.

Is thermal conductivity relevant in insulation materials?

Yes, low conductivity is desirable for insulation.

Can materials be engineered to have specific thermal conductivities?

Yes, through material composition and structure.

Is thermal diffusivity important in building materials?

Yes, it influences how buildings respond to temperature fluctuations.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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